Oxide-promoted titanium-phosphorus catalyst



No Drawing. Application December 1, 1952, Serial No. 323,518

15 Claims. (Cl. 252-437) The present invention relates to a catalytic material of improved properties in the promotion of hydrocarbonconversion reactions. More particularly, the invention relates to a solid catalyst of high activity and long life, consisting essentially of an oxide-promoted reaction prodnet of a titanium halide and a phosphoric acid.

Titanium chlorides. and bromides, like aluminum chloride and various other catalysts of the Friedel-Crafts type, are excessively active in promoting various types of reactions for which they are otherwise satisfactory catalysts. It would therefore be a desirable improvement to subject the titanium halides to some form of physical or chemical treatment capable of moderating their excessive catalytic activity. Such a treatment is described in our copending application, Serial No. 323,517, filed Decemher 1, 1952, wherein a titanium halide is commingled and heated with a phosphoric acid at a temperature above about 175 C. until the evolution of hydrogen halide substantially ceases. Catalysts of greatly improved properties are obtained thereby, efiective in a wide range of hydrocarbon-conversion reactions, such as the polymerization of olefins, the .isomerization of olefins, the alkylation of aromatics, the desulfurization of sulfur-containing stocks, and the like. 1

We have now discovered that a catalyst offurther improved properties can be obtained by heating a titanium chloride or bromide with orthophosphoric acid or pyrophosphoric acid in the presence of a metallic oxide having hydrogenation-dehydrogenation properties. The reaction is continued at a temperature and for a time sufiicient to drive oil hydrogen halide equivalent to substantially all of the halogen in the titanium halide, and a gray,

riable solid is obtained thereby of high activity, high selectivih and low coke-forming tendencies.

One object of our invention is to prepare an improved hydrocarbon-conversion catalyst. Another object is 'to prepare a catalyst of high selectivity. in the polymerization, alkylation, isomerization, and desulfurization of hyrocarbons. A further object is to prepare a titaniumbased catalyst of moderated activity and improved selectivity. Another object is to prepare an oxide-promoted, acid-modified, titanium-based catalyst. Another object is to prepare a solid titanium-based catalyst. Other objects of the invention audits superiority .over the prior art will be apparent from the present description and claims.

A convenient method of'preparing our new catalyst is to suspend or dissolve a group V or group VI metallic oxide, preferably the latter, in phosphoric acid in a stirred vessel, commingle titanium halide therewith, and then ted States Patent m .m l i to 1 .1 atemp ur th t h dro en halide is evolved smoothly in a steady stream. The reaction begins at ordinary temperatures, andproceeds rapidly at to 'C.. As hydrogen halide evolution slows down, the temperature is raised gradually or SE P wise to a maximum of C. or above, preferably be 'tween about 175 and 250 C., optimally around 200 -C.,

where it is maintained until hydrogen halide evolution has approached the theoretical (e. 'g., 3.5 to..4 moles permole of titanium tetrahalide) 'and'haspractically ceased, and

ice

temperature above about 175 C. for a suflicient length of time to drive off hydrogen halide in a quantity approaching the theoretically derivable amount, the most active catalysts being obtained at about 96 percent or more of the theoretical hydrogen halide evolution. Inadequate heating produces a yellow, inactive catalyst, which, however, can be converted into the gray, highly active material by a supplemental heating under the defined conditions.

An alternative procedure which may be followed is to dissolve or suspend the group V or group VI metallic oxide in the titanuim halide, then add the acid, and heat as before. As a further alternative, the titanium halide and the phosphoric acid may. be commingled, and the metallic oxide may be added thereto either before or during the subsequent heating step. As a still further alternative, the reaction of titanium halide and phosphoric acid can be carried out in the presence of a substance, e. g. chormic acid, ammonium molybdate, vanadic acid, and the like, afiording an oxide of the defined type under the reaction conditions employed. In general it can be said that any manipulative procedure which effects the reaction of phosphoric acid with tatanium halide in the presence of a group V or group VI metallic oxide having hydrogenation-dehydrogenation properties, and which results in the evolution of substantially the theoretical proportion of hydrogen halide, will be suitable for preparing our new catalyst composition.

Catalysts of our new class can satisfactorily be prepared from titanium tetrachloride, titanium tetrabromide, and other titanium chlorides and bromides. Suitable acids include orthophosphoric (HJPOt) and pyrophosphoric acids, the former being preferred. As activators, we may suitably use oxides of group V or group VI metals having hydrogenation-dehydrogenation properties, such as chromia, molybdena, vanadia, urania, tungsten oxide, and the like. The proportion of such oxide should be between about 0.5 and 20 percent by weight, preferably between about 1 and 5 percent by weight, based on anhydrous phosphoric acid. Titanium tetrachloride, for example, reacts readily with orthophosphoric acid and gives good yields of solids which vary in consistency according to the ratio of the reactants. Semisolids are obtained when as little as 0.24 mole of TiCh is allowed to react with one mole of H3PO4 in the presence of the minimum proportion of promoting oxide, while dry solids are obtained at a ratio of 0.38 or more. At ratios higher than about 0.7 mole per mole, the reaction product contains unrea'cted TiCll; such higher ratios should therefore be used onlywhere the presence of the resulting free TiClr in the reaction product is not objectionable. In general, we prefer to contact titanium halide with phosphoric acid H3PO4 in a molar ratio between about 0.4:1 and 0.6:1.

The reaction proceeds more readily and gives higher yields if the phosphoric acid is anhydrous or substantially in an atomic ratio of halogen to active hydrogen between about0.4:-l and 1:1, and we prefer to contact TiCLi with anhydrousi. e., contains less than about 2.5 percent by Weight of water. i e i Our new'catalysts is a stable solid, and does not ordinarily require the use of a supporting material.

The catalysts described herein are useful in a varietyof hydrocarbon-conversionreactions. They 'may, for ex- .rnatics or isoparaffins olefins or olefin-aiifording sub stances, the isomerization of parafiins, the s i d. e t:l1ain 91,6- ydr g n on f alky uhst 'tuted Ar en ina-th I ment of motor fuels to increase their .antiltnock rat ng, the original yellow color of the mixturehaschangedto' gray. it is important to subject the reactioumixtur'e to a ample, be used under conventional conditions for the polymerizations of unsaturated hydrocarbons to form liquids ofhig her molecular weight, thealkylation of aroand the lilteb l liminary to the dehydrogenation or simultaneously with it.

The simultaneous isomerization and dehydrogenation reactions are readily accomplished by use of our new catalysts, whichmoreover perform the desired function with a of'side reactions such as coke and gas formation and with a" maximum yield of the desired aromatics; In general, the hydrocarbon stream to'be isomerized and .dehydrogcnated should be passed over our catalyst'at a temperature .in' the range of 150 to 500 C., .preferably:200 to 450 C. Hydrogen should be cycled over'the catalyst with the charging stock at a hydrogen partial'pressure in the range of 100 to 5000 pounds per square inch, preferably 200 to 1000 pounds per square inch. The liquid hourly space velocity may suitably lie within the range of about 0.5 to 4.

'Our catalysts are outstandingly effective in the removal of sulfur from petroleum fractions containing organic sulfur compounds, as described in the copending application of Wilford J. Zimmerschied and Harold Shalit, Serial No. 323,520, filed December 1, 1952, now U. S; Patent 2,726,991. out most advantageously at a temperature between about 200 and 500. C.,'preferably 350 to 450 C., a hydrogen pressure up to about 1500 pounds per square inch'or above, preferably 200 to 1000 pounds per square inch, and a liquid hourly space velocity between about 0.5 and 4.

Our catalyst is conveniently employed as a powder, slurried in the charging stock, or as solid particles, pellets The total product yield, based on the charging stock, was 80 volume-percent. V a a In contrast to the above results, an unpromoted TiCl4- HsPO4. catalyst was substantially less "effective in desulfurizing a West Texas virgin naphtha. Into a flow reactor .were placed 40 milliliters (43.3 grams) of: a ,4 7

inch pelleted catalyst prepared by heating 103.5 grams (approximately 1 mole). of anhydrousHaPOswith 122 grams (0Q64mole) of TiCl4 to a temperature ranging from 150 to 200 C. for one hour. Thereactor was heated'to a temperature of 395 C- and pressured with hydrogen at 600 pounds per square inch, andthrough 'it'was passed a vaporizedstream of West 'Texas virgin naphtha. (0.324

percent sulfur) at aliquid hourly space"velocity' of 2.

A 98 volume-percent yield of liquid product containing 0.114% sulfur-was obtained, corresponding to aidesu'l The product was collected in two fractions, which were The desulfurization is carried i or'pills, in a fixed or moving bed. Numerous alternative processes and reactor designs will 'be apparent to those skilled in the art. j

Our invention will be more fully understood from the following specific examples.

Example 1 A solid catalyst'was prepared by heating a mixture of V 98- grams of anhydrous H3PO4, two grams of CrOs, and

72.9 grams of TiCl-i to a temperature ranging from 150 to 200 C; until HCl evolution substantially ceased. The

resulting solid was formed into 14-inch pellets.

The catalystobtainedjinthis way is suitable for ef- V fecting the simultaneous isomerization and, dehydrogenation of methylcyclopentane at a temperature around 400 C., a-hydrogen partial pressurearound 1000 pounds per square inch, and a liquid hourly space velocity of. about I .l, producing benzene in'good yield. e

V EqciampZe Intoa flow reactor were placed '50 milliliters of the pelleted catalyst described in Example .1. The reactor was heated to a;temperature of 385 C. and pressured with hydrogen to 960 pounds per squareinch, and through it wasa passed a vaporizedrstream of West Texas virgin naphtha at a liquid hourly space velocity of V 1.2. *The product was collected 'in two fractions, which were analyzed separately. The results were as follows:

Desulfurtzation, perimnr ,sented in'the following table:

analyzed separately, with the following results:

Product Charging Stock Fraction Fraction Aromatics content, vo1.percent Desuliurization, perce observed aromatics and olefin cont ents of fraction 1 indicated that extensive alkylation of aromatics hadtaken' place. f

Example4 r Orthophosphoric- .acid (114 grams), titanium tetra- V chloride (]grams) and molybdenum trioxide, MoOs (2.3 grams), were mixed and heated'to a maximum of 86 C, for 17 hours. The temperature was then raised to a maximum of 200C." over a'period of 6 hours. The reaction product was outgassed' in a vacuum oven at C., and was finally crushed and formed into /8- inch pellets. The pelleted catalyshhavinga crushing strength of 5 to 7 pounds, 'was tested in the vapor-phase desulfurization of a West-Texas virgin iheavy naphtha containing 0.355 percent by weight of sulfur. .The'treated naphtha was collected in two fractions, which were analyzed separately. For comparison, similar .tests were run on an .unpromoted Tito? catalyst, prepared according to substantially the same procedure by reacting 151.5

grams of anhydrous orthophosphoric. acid with 194.6

The results are pregrams of titanium' 'tetrachloride.

tion, a

ride (126 grams); and; hydrous tungsten trioxide, WOsJ-IzO (3. grams), were.inixed,1and was observed that HCl was liberated and a fiuify, yellowish, solid mass was formed before heat was applied. The mixture was heated to a maximum of 80 C. for 18 hours, and the temperature was then raised over a period of 8 hours to 205 C. The reaction product was dried in a vacuum oven and formed into /e-inch pellets having a crushing strength of 6 to 8 pounds. The completed catalyst was tested as described in Example 4, with the following Orthophosphoric acid (98 grams), titanium tetrachloride (95 grams), and vanadium pentoxide, V205 (2 grams), were mixed, heated, dried, and pelleted as described in Example 5. The pellets had a crushing strength of 6 to '7 pounds. The completed catalyst was tested as described in Example 4, with the following results:

Prod- Liquid uct Product esul- Promoter Temp Press Sp. Yield, S, w't.- iuriza- C. p. s.i. g VeL, vol.- percent tion,

hr.- perpercent cent V205 390 1,000 i 1.9 2g 8:832 V105 400 200 1.0 2g 8: g None 208 1,000 1.0 92 None. 410 1,000 1.8

While the foregoing specific examples illustrate advantageous embodiments ofour invention, it is-to be understood that we are not limited thereto, but rather that the truescope; of our invention is evidenced by the broad disclosure thereof and by the appended claims. In general it can be said that any modifications or equivalents of our invention that would ordinarily occur to one skilled in the art are to be considered as lying within the scope of our invention.

Our new catalyst compositions are comparatively in-- expensive and conveniently made. They are stable in contact with air, and do not tend to form massive aggregates in the presence of water. They are highly active for many hydrocarbon conversions; nevertheless, they are quite selective, and have so little tendency to cause disproportionation, coke deposition, and other side reaction that they have a long useful life.

In accordance with the foregoing description, we claim as our invention:

l. A process for'the manufacture of a solid, selfsupporting catalyst which consists essentially of mixing a substantially anhydrous phosphoric acid selected from the group consisting of orthophosphoric and pyrophosphoric acids, a titanium halide selected from the group consisting of the chlorides and bromides of titanium in anatomic ratio of halogen to acive hydrogen in said acid between about 0.4:1 and 1:1, and a promoter in a concentration between about 0.5 and 20 percent by weight based on said acid, said promoter being selected'from the class consisting of groups V and VI metallic oxides having hydrogenation-dehydrogenation properties, and

'6 heating the resulting mixture at a temperature above about C. until evolution of hydrogen halide therefrom substantially ceases and approximates the theoretical quantity of hydrogen halide.

2. A process for the manufacture of a solid, self-supporting catalyst which consists essentially of mixing a titanium chloride with substantially anhydrous orthophosphoric acid in an atomic ratio of chlorine to active hydrogen between about 0.421 and 1:1 and between about 0.5 and 20 percent by weight based on said acid of an oxide of a metal chosen from groups V and VI, said oxide having hydrogenation-dehydrogenation properties, and heating the resulting mixture at a temperature above about 175 C. until evolution of hydrogen chloride therefrom substantially ceases and approximates the theoretical quantity of hydrogen chloride.

3. A process for the manufacture of a solid, self-supporting catalyst which consists essentially of mixing titanium tetrachloride with substantially anhydrous orthophosphoric acid in a molar ratio above about 0.38:1

and between about 0.5 and 20 percent by weight based on said acid of an oxide of a metal chosen from groups V and VII, said oxide having hydrogenation-dehydrogenation properties, heating the resulting mixture to a temperature above about 175 C.- to promote interaction of the components thereof with evolution of hydrogen chloride, and continuing said heating until said evolution of hydrogen chloride exceeds 3.5 moles per mole of titanium tetrachloride and substantially ceases.

4. A process for the manufacture of a solid, self-supporting catalyst which consists essentially of mixing titanium tetrachloride with substantially anhydrous orthophosphoric acid 'in a molar ratio between about 0.38:1 and 0.721 and between about 1 and 5 percent by weight based on said acid of an oxide of a metal chosen from groups V and VI, said oxide having hydrogenationdehydrogenation properties, heating the resulting mix ture to a temperature above about 175 C. to promote interaction of the components thereof with evolution of hydrogen chloride, and continuing said heating until said evolution of hydrogen chloride exceeds 3.5 moles per mole of titanium tetrachloride and substantially ceases.

' 5. A process for the manufacture of a solid, self-' supporting catalyst which consists essential of mixing substantially anhydrous orthophosphoric acid, between about 1 and 5 percent by weight of chromia based on said acid, and between about 0.38 and'0.7 mole ofititanium tetrachloride permole of said acid, and heating the resulting mixture to a temperature between about 175 and 250" C. until the evolution of hydrogen chloride therefrom exceeds 3.5 moles per mole of titanium tetrachloride and substantially ceases.

.6. A process for the manufacture of a solid, self-.

supporting catalyst which consists essentially of mixing substantially anhydrous orthophosphoric acid, between about 1 and 5 percent by weight of molybdena based on said acid, and between about 0.38 and 0.7 mole of titanium tetrachloride per mole of said acid, and heating i the resulting mixture to a temperature between about 175 and'250 C. until the evolution of hydrogen chloride therefrom exceeds 3.5 moles per mole of titanium tetrachloride and. substantially ceases. f

S. An oxide-promoted titanium-phosphorus catalyst composition prepared by the process which consists esmetal'chosen fromv groups V and VI; said oxide having art 3.

sentially of mixing a substantially anhydrous phosphoric acid selected from the; group consisting of orthophosphoric and pyrophosphoric acids, a titanium halide selected from the group consisting of the'chlorides and bromides of titanium in an atomic ratio of halogen-to active hydrogen in said acid between about 0.4:1and' 1:1, and a promoter in a concentration between about 05 and 20 percent by weight based on said acid, said promoter being selected from'the class 'consistingof groups V and VI metallic oxides having hydrogenationdehydrcgenation properties, and-heating the resulting mixture at a temperature above about 175 C. until evolution of hydrogen ,halide therefrom substantially ceases and approximates the'theoretical quantity o f hydrogen halide:

- f 9. An oxide-promoted titanium-phosphorus catalyst 7 composition, prepared by the process which consists essentially of 'mixing a titanium chloride'with' substantially anhydrous orthophosphoric acid inan atomic ratio 'of chlorine to active hydrogen between about 0.421 and 71:1 and between about 0.5 and 20 percent by weight based on said acid of an oxide of a rtnetal chosen from groups V and 'VI, said oxide having hydrogenation-dehydrogena tion properties, and heating the 'resulting rnixture at a temperature above about- 175 C. until evolution of hydrogen chloride therefrom substantially ceases and approximates the theoretical quantity of hydrogen hl ride a V .5 a 2 n r 10; An. oxide-promoted titanium-phosphorus catalyst composition, prepared by the process which'consists es sentially of mixing titanium tetrachloride with substantially anhydrous orthophosphoric acid in a'molar ratio above about 0.38:1 and between'about 0.5'811Cl percent by weight based on said acid'o f' an oxide of a hydrogenation-dehydrogenation properties, heating the 7 resulting mixtureto a temperature aboveJabout v1'75 C, to promote interaction of the components thereof with evolution of hydrogen chloride, and continuing said heating until said evolution of hydrogen chloride exceeds 3.5 moles per mole of titaniumtetrachloride and sub:

stantially ceases.

.11. An. oxide-promoted titanium-phosphorus catalyst composition, prepared by the process which CQDSiStS S- sentially of mixing; titanium tetrachloridewith substan 5 tially anhydrous orthophospho'ric acidina molar ratio between about 0.38:1 and 0.711 and between aboutjl and 5 percent by weight based on said acid of an oxide of'a metal chosen from groups V and V1, said oxid e having hydrogenanon-dehydrogenation properties, heat ing the resulting mixture toa'temperature above about C. to promote interaction of the components thereof with evolution of hydrogen chloride, and continuing acid, and heating the resulting mixture to a temperature between about 175 and 250 C. until the evolution of hydrogen chloride therefrom exceeds 3.5 moles per'mole of titanium :tetrachloride'and subs'ta'ntially ceases.

13. A molybdena-promoted}titanium-phosphorus catalyst composition, prepared by the, process which consi's'tse'ss'entially' of mixing substantially anhydrous ortho phosphoric acid, betweem-about g1 and :5 percent by: weight of niolybdena based on said acid, and between about 0.38 and 0.7 mole of titanium tetrachloride per mole of said acid, and heating the resulting mixture to.

atemperature between about 175 and 250 Cliifitil the 'evolution'of hydrogen, chloride therefrom exceedsBlS.

moles permoleof titanium-tetrachloride and substan tially ceases.

14. A tungsten oxide promoted titanium-phosphorus catalyst composition, prepared by the" process which consists essentially of mixingsubs'tantially anhydrous ortho phosphoric acid; between about 1 and 5 percent by weight of tungsten -oxide' based on .said"acid,fand bet'ween'about 0.38 and 0.7 mole of titanium tetrachloride per mole of 'said' acid, andh'eating the resulting mixture to a temperature between about 175 and-2-50 C. until the evolution of hydrogen chloride therefrom exceeds 3J5 moles per mole 'of titaniurrntetrachloride and sub- Q stantially ceases. V

15. A'process for themanufacture of a solid, selfsuppofiing catalyst which. consists essentiallyi of, mixing substantially anhydrous orthophosphoric acid, between about l andiabout 5% by weight of vanadiumpentoxide, 7 basedon said acid and; between about 0.38 and.0. 7. mole of titanium tetrachloride per mole of said acid, andheating the resulting mixture to a temperature between about 175 and 250? C. until the'evolution of hydrogen chloride therefrom exceeds 3.5 moles per mole of titanium'tetrachloride and'substantially ceaees. p ;"ReferencesCitdinthe this' pate'nt V UNITED sTATas -PATENTS 2,358,011 1 1}Ipatieff net '31." I Sept. 12, H 2,365,895 Mavity, p n s. 26, 1944 2,569,092- Deering, Sept. 25,

2,608,534 Fleck t Aug. 

1. A PROCESS FOR THE MANUFACTURE OF A SOLID, SELFSUPPORTING CATALYST WHICH CONSISTS ESSENTIALLY OF MIXING A SUBSTANTIALLY ANHYDROUS PHOSPHORIC ACID SELECTED FROM THE GROUP CONSISTING OF ORTHOPHOSPHORIC AND PYROPHOSPHORIC ACIDS, A TITANIUM HALIDE SELECTED FROM THE GROUP CONSISTING OF THE CHLORIDES AND BROMIDES OF TITANIUM IN AN ATOMIC RATIO OF HALOGEN TO ACTIVE HYDROGEN IN SAID ACID BETWEEN ABOUT 0.4: AND 1:1, AND A PROMOTER IN A CONCENTRATION BETWEEN ABOUT 0.5 AND 20 PERCENT BY WEIGHT BASED ON SAID ACID, SAID PROMOTER BEING SELECTED FROM THE CLASS CONSISTING OF GROUPS V AND VI METALLIC OXIDES HAVING HYDROGENATION-DEHYDROGENATION PROPERTIES, AND HEATING THE RESULTING MIXTURE AT A TEMPERATURE ABOVE ABOUT 175* C. UNTIL EVOLUTION OF HYDROGEN HALIDE THEREFROM SUBSTANTIALLY CEASES AND APPROXIMATES THE THEORETICAL QUANTITY OF HYDROGEN HALIDE. 